This article is intended to be a general guide to writing character pages. A blank template for characters can be found here.
Depending on the character you are writing about, there may be a lot of information or a little. If there is only a little info, then you can basically write one or two paragraphs and be done with it (citing references, of course) but if it is a major or recurring character, then you will have more information to provide, and should follow these guidelines.
Description[]
The very first thing to write is a brief outline of the character -- who they are, what their relationship to the show is and what their general MO might be. Save the detail for the following sections.
Character Background[]
This is where you provide more detailed information.
Origins[]
Here you might state where the character first appeared and what the circumstances were. If there is any special reason why they appeared on the scene, this is where it should go.
Living Arrangements[]
Talk a little about their whereabouts, whether they live in Sunnyvale or not, and if they've moved around (people in the show tend to do that a lot).
Love Life[]
Like their living arrangements, this tends to change without warning in Sunnyvale, and this is the place to talk about who's seeing who and why.
Criminal Activity[]
... Another big part of life at the park. Try to be specific about exactly what the character is into (or not) and what might have happened in this area.
Other Information[]
Not a required section, this is a catch-all for other information that might not fit the other categories. For example, on the J-Roc article, there is a section called 'The Rap Game' which details his music career. You can add sections in here as you wish, just let's not call it something as mundane as 'Other Information'
Characterization[]
This section is reserved for miscellaneous fats about how the character acts, dresses, carries themselves or for any other details that make them unique in the show. You can pretty freely fill out this section as much as you like, as long as none of the information here is also mentioned in the previous sections.
Referencing[]
Reference points in your article where applicable, the easiest place being at the ends of paragraphs. See the 'Using References' article for the best ways to reference your sources.
Chronology[]
Wherever possible, detail each section in order from earliest to latest, to keep the timeline in tact. It may not be consistent, but make your best effort.
Keep It In Character[]
There are a few exceptions, but try to keep your article on the topic of the character, and don't delve into the actor that plays the part -- that's what the actor articles are for. Use your best judgement.